Since optical discs such as a CD (Compact Disc) and a CD-ROM (Compact Disc Read Only Memory) are easy to handle and are produced at relatively low cost, they have been widely used as recording mediums for storing data. In recent years, a CD-R (Compact Disc Recordable) disc, on which data can be recorded once, and a CD-RW (Compact Disc ReWritable) disc, on which data can be rewritten, have come out. Thus, data can be easily recorded on such recordable optical discs. As a result, optical discs that accord with the CD standard such as a CD-DA disc, a CD-ROM disc, a CD-R disc, and a CD-RW disc have become the mainstream of data recording mediums. In addition, in recent years, audio data is compressed according to the MP3 (MPEG1 Audio Layer-3) and the ATRAC (Adaptive TRansform Acoustic Coding) 3 and recorded on the CD-ROM disc, the CD-R disc, the CD-RW disc, and so forth.
However, as a CD-R disc and a CD-RW (Compact Disc ReWritable) disc have come out, data recoded on a CD disc can be easily copied to those discs. As a result, a problem about copyright protection has arisen. Thus, when content data is recorded to a recordable optical disc, it is necessary to take measures to protect content data.
FIG. 1 shows an outline of a flow of a copying process. A reproducing apparatus denoted by reference numeral 41 reproduces data from an original disc, for example a CD 42. Reference numeral 43 represents an optical pickup. Reference numeral 44 represents a reproduction signal processing portion. Reproduced data is supplied from the reproducing apparatus 41 to a recording process portion 52 of a recording apparatus 51. An optical pickup 53 records the reproduced data to an optical disc, for example a CD-R disc 54. The recorded contents for example recorded data of the original CD 42 are copied to the CD-R disc 54. Using the reproducing apparatus 41 and the recording apparatus 51, a copied disc of the original CD 42 can be easily produced.
In the case of a CD, as shown in FIG. 2, a sync detecting portion 46 of the reproducing process portion 44 detects a frame sync from a reproduced signal supplied from an input terminal 45. An EFM demodulator 46 EFM (eight to fourteen modulation) demodulates the reproduced signal and supplies the EFM-demodulated reproduced data to a CIRC (Cross Interleave Reed-Solomon Code) decoder 48. The CIRC decoder 48 corrects an error of the reproduced signal. In the EFM, each symbol (eight data bits) is converted into 14 channel bits and connection bits of three bits are added between adjacent strings of 14 channel bits. A sub code decoder 49 decodes the reproduced data and obtains a reproduced sub code.
FIG. 3 shows an outlined structure of the recoding process portion 52. Data to be recorded is supplied from an input terminal 55 to an CIRC encoder 56. The CIRC encoder 56 performs a CIRC encoding process for the data supplied from the input terminal 55. In addition, a sub code is supplied from an input terminal 57 to a sub code encoder 58. The sub code encoder 58 formats the sub code. An output of the CIRC encoder 56 and an output of the sub code encoder 58 are supplied to a multiplexer 60. In addition, a frame sync is supplied from an input terminal 59 to the multiplexer 60. The multiplexer 60 arranges those data in a predetermined order. An output of the multiplexer 60 is supplied to an EFM modulator 61. The EFM modulator 61 performs an EFM modulating process for data that is output from the multiplexer 60.
As one method for protecting content data recorded on a CD disc, it is determined whether the disc is an original CD or a CD copied from an original CD. When the disc is an original CD, a copying operation thereof can be permitted. When the disc is a copied disc, a further copying operation thereof can be prohibited.
To determine whether the disc is an original disc or a copied disc, a method for placing a defect on a disc in a master disc production stage, detecting the defect from a disc during a reproduction, and determining that the disc is an original disc based on the detected defect. In this method, however, an original disc may contain such a defect. In addition, depending on the type of a defect, it may be copied as it is. Thus, content data of an original disc cannot be prevented from being copied to a CD-R disc.
An object of the present invention is to provide a data recording medium and data recording method and apparatus that can determine whether a disc is an original disc or a copied disc and prevent a copying operation depending on the determined result without need to intentionally place a defect on the disc.